Just install xp on the new drive, without the old one connected to be safe.
Then when complete, change the jumpers on your hard drive to make it slave and connect it to your 80gig ribbon. Either that, or put it as it is on the other ide ribbon and change your cd to be a slave.
Xp will boot from the 80gig and you will see your old drive in my computer. Just copy over what you want and then when you're sure you have everything, format it in windows.
IF you are using OUTLOOK, make sure you set up xp pro on the new 80gig with the same user name. It can otherwise be a pig to get your emails back in.